The overall objectives of this project are to attempt to identify the individual differences in the behavioral repertoire of infants and to determine how these differences interact with environmental experience to result in particular developmental outcomes in normal and risk populations. In pursuit of these individual differences, we have been developing an observational system designed to record environmental events in sufficient detail so as to permit an individual environment interaction analysis. A data base on over 300 infants has been accumulated using the NBAS-K (Neonatal Behavioral Assessment Scale with Kansas Supplements) and a reliable observation system of early infant environments has been developed. The program of proposed work for the coming year includes the extension of data collection on the sample of normal infants and the beginning of data collection on NBAS-K used with samples of risk infants. In addition, follow-up work will begin with a core sample of normal infants such that further evaluations will occur in the home during the first four months of life both in terms of infant behavior and in terms of environmental observations.